GPS has been applied with much success to guided projectiles. The overwhelming capabilities of GPS guided projectiles yields an overreliance on the GPS system. Due to the possibility of natural and man-made threats to the availability of GPS technologies to remain fully functional and properly operating during navigation, provision must be made for GPS-denied navigation of spin-stabilized projectile munitions, especially in the battlefield environment.
GPS systems provide navigation data (i.e., position, velocity, time) required by the guidance and flight control systems of projectiles for successful course correction to a target. A gun-launched environment often makes it difficult to collect quality data from alternate (i.e., non-GPS) feedback sources, such as inertial sensors, seekers, or data links. The physical forces generated by a gun launch may alter the basic functionality of sensor devices, which then obfuscates ground calibration. Additionally, spin-stabilized projectiles rotate hundreds or thousands of times per second, which severely stresses the dynamic range and integration of sensors such as accelerometers and gyroscopes. Component survivability and operational performance of onboard spin-stabilized projectiles are also major concerns since quality measurement data is required for accurate navigation. Lastly, cost is a major factor since ballistic projectiles are relatively inexpensive and it would be desirable to develop a low-cost solution for accurate navigation in a GPS-denied environment. The overall cost of a navigation system is often driven by the measurements required to develop input for the navigation system. The use of micro-electromechanical (MEM) accelerometers as low-cost measurement sensors is desirable, but such sensors often feature higher noise characteristics than more expensive accelerometer technologies. Additionally, unduly high labor cost is sometimes required to calibrate these measurement technologies into a final integrated flight vehicle.
Therefore there is a need in the art for a relatively low-cost GPS-denied navigation system for spin-stabilized projectiles.